Question and Answer website

Hello Looking to create a social interactive question and answer website with a unique design , features are similiar to yahoo answers and qora . You can use any pre existing script but the script should be customisable and scaleable and have a easy backend to manage .Website should be SEO friendly. You would have to design the website and also be able to cutsomise the features add /remove etc.I am looking at a creative design and simple design. I am looking at completing this project in 3 weeks to have the beta version rolled out.